Idle governor



y 0, 1965 N. J. BECK 3,195,525

IDLE GOVERNOR Filed March 9, 1964 2 Sheets-Sheet 1 IN VEN TOR.

WHANN 8 McMAN/GAL lll/omays fbr A b'mn/ July 20, 1965 Filed March 9, 1964 N. J. BECK IDLE GOVERNOR 2 Sheets-Sheet 2 INV EN TOR.

United States Patent 3,1@5,525 EDLE GUVERNGR Niels Johannes Beck, Miraieste, Calif., assignor to Me- *Culloch Corporation, Los Angeles, Calif., a corporation of Wisconsin Filed Mar. 9, 1964, Ser. No. 350,158 7 Claims. (Cl. 123-73) This invention relates generally to governors for internal combustion engines and relates more particularly to speed governors for combustion engines.

While the invention has utility embodied in a governor for governing the speed of two-cycle internal combustion engines, and is shown and described as thus embodied, it is to be understood that its utility is not confined thereto since it may be used with four cycle internal combustion engines or other types of internal combustion engines.

It is a general object of the present invention to provide a novel and improved governor mechanism for use with internal combustion engines.

More particularly, it is an object of the invention to provide a governor or governing device subjected to and operatively related to pressure pulsations such as the pressure pulsations in the crankcase of a two-cycle internal combustion engine.

It is another object of the invention to provide a device of this character that can be embodied in a small, lightweight unit.

It is still another object of the invention to provide a device of this character that will fit into a relative small space.

It is a further object of the invention to provide a device of this character that is relatively powerful.

It is a still further object of the invention to provide a device of this character that is extremely simple in construction and has a minimum of moving parts.

It is another object of the invention to provide a device of this character that requires no connection to rotating parts of the engine to operate same.

It is still another object of the invention to provide a device of this character that is totally enclosed to thereby provide maximum protection against the entrance of dirt or other foreign matter.

It is a further object of the invention to provide a device of this character that provides maximum protection against tampering by unauthorized persons.

It is a still further object of the invention to provide a device of this character that may be readily serviced.

It is another object of the invention to provide a device of this character that is relatively inexpensive to manufacture.

The characteristics and advantages of the invention are further sufficiently referred to in connection with the following detailed description of the accompanying drawings, which represent certain embodiments. After considering these examples, skilled persons will understand that variations may be made without departing from the principles disclosed and I contemplate the use of any structures, arrangements, or modes of operation that are properly within the scope of the appended claims.

Referring to the drawings, which are for illustrative purposes only:

FIG. 1 is a schematic View of a two-cycle internal combustion engine having a governor embodying the present invention connected thereto;

FIG. 2 is a schematic end View of the governor with a portion thereof in section to show the interior mechanism of the pneumatic throttle actuator;

FIG. 3 is a longitudinal schematic sectional view taken on line 3-3 of FIG. 2; and

FIG. 4 is a view, partially in section, of an alternative actuator arrangement.

3,195,525 Federated July 20, 1965 p ce Referring more particularly to FIG. 1, there is shown an internal combustion engine of the two-cycle type, indicated generally at 11), having a crankcase 11 and a cylinder 12. A crankshaft 14 is disposed in the crankcase and has a crank arm 15 with a crank pin 16 to which is operably connected a connecting rod 17. Connecting rod 17 extends upwardly in the cylinder 12 and is operably connected to a piston 18 by the usual well known means which includes a wrist pin 19.

There is a fuel mixture inlet port 20 for the cylinder 12, said fuel mixture inlet port being connected with the crankcase by means of a conduit 21. Opposite the fuel mixture inlet port 20 there is an exhaust port 22 having an exhaust manifold 23 attached thereto. The fuel mixture inlet port for the cylinder and the exhaust port are arranged in the usual manner for two-cycle internal combustion engines.

The crankcase 11 has an inlet 25 of the usual character which is adapted to have the fuel mixture outlet of a carburetor, indicated generally at 26, attached thereto. At the inner end of the crankcase inlet passage there is the usual reed value 27.

While any type of carburetor may be used and controlled by the present governor mechanism, a pulse-type carburetor is shown. This carburetor 26 has a throttle shaft 28 through which the usual throttle valve 29 is secured within the fuel mixture outlet passage 30 of the carburetor 26. One end of the throttle shaft 28 projects outwardly of the part of the carburetor in which said throttle shaft is journaled and there is a throttle lever,

31 secured to this projecting end.

A governor, indicated generally at 35, is secured to the carburetor by any suitable well known means, such as screws or the like, not shown, and said governor includes an actuator rod 36 pivotally connected at 37 to one end of a link 38, the opposite end of said link being pivotally connected at 39 to the throttle lever 31 adjacent the free end thereof.

Details of the two major components of the mechanism, the throttle actuator, indicated generally at 45, and the vibrating valve, indicated generally at 46, are shown as combined in a single casting. However, this is not a requirement as these components may be separate units operatively connected together.

Referring now to FIG. 2, the throttle actuator mechanism includes an actuator housing 47 having a cylinder 48. While the cylinder may be otherwise positioned, it is shown as having its axis vertical. At the upper end of the cylinder there is an enlarged diameter groove 49 with a shoulder 50 at its inner end normal to the axis of the cylinder. A disc 51 is press-fitted into the groove 49 to close and seal the upper end of the cylinder.

At the lower end of the cylinder 48 there is a similar enlarged diameter groove 5-3 having a shoulder 54 at its inner end normal to the axis of the cylinder 48. A seal 55 is disposed in the groove 53, said seal having an axial opening 56 therein. Seal 55 is secured in groove 53 by means of a spring retainer 57 of any well known character.

Within the cylinder 43 there is operably disposed a piston 60 which includes a depending axial boss 61 of reduced diameter. There is a bore 62 which extends axially through the piston and in which is received a piston rod 63. Piston rod 63 is secured to the piston 60 by means of a pin 64 received in aligned openings provided therefor in the boss 61 and piston rod 63. Piston rod 63 has a lower end portion which extends through the opening 56 in the seal 55 and projects downwardly therefrom. A cross-bore 66 is provided the lower projecting end portion of the piston rod whereby said rod may be pivotally secured to the link 38 or other member to be actuated by the piston mechanism. There is an upper end portion 67 of the At the upper end of the cylinder 48 there isafiuid port I V 72 vwhichconn-nunicates at all times with the clearance space. Adjacent the a fluid port 73.

Referring to FIG. 3,'the vibrating shuttle valve mechanism comprisesan elongated body 8%) having a longitudinally extending bore 81 therethrou-gh in which is secured a sleeve 82, said sleeve being secured in'the bore $1by any suitable well known'means, such-as a press fit,.fo'rfexample. tudinally extending bore .83.

Bore 83 may be considered a bore of the valve mechanism and one end of said bore 83 is closed by'a plug 84' having a recess 85 in the inner end, there being a: shoulder 86 at the inner end of said recess.

At the opposite end of the valve body there is a cover, indicated generally at 88, and comprising a discs? with an axially arranged inwardly. projecting boss 99 having an axial recess 91 at the inner end which terminates at its outer end in a shoulder 92. Boss 9% is of smaller external diameter than-the diameter of the bore 81 of the body 86), so as t-obe receivablethere-in. It-i's't'o be noted that the adjacent end of the sleeve 82'is spaced inwardly of the inner end of the boss99. A gasket s3 is disposed between the disc portion 89 of the cover and the adjacent end of the body 80, said cover-and gasket being secured to the body by screws 94. Cover 88 is provided with a longitudi-' nally extending passage 95 'therethrou-gh in which is se-' cured, as s a press-fit or other suitable means, an end portion 96 of a conduit 97 which has its opposite end connected to the interior of the crankcase 11 of the engine. Conduit 97 thus transmits pressure pulsation from the crankcase to-the adjacent end of the bore or cylinder 33 of the valve mechanism. It is to be understood, of course, I

eter, there being valve headsllOZ and 1&3 at the respective lowerends 'of the cylinder 48 there is Sleeve 82'is tubular and defines a'cylindrical longiv of the bore 83 of the valvemechanisin at the end adjacent thecover, the portion of said bore thus subjected to crankcase pressure pulsations is indicated at 118 and these pressure. pulsations are then transmitted through the longitudinal passage 116 of the spool valve, through the crossbore and into the annulus 126. defined by the reduced diameter'section ltll of the spool valve and the adjacent portion of the wall of the bore 83.

Bore 33Yhas a port A which communicates by way of a short passage 122 with a passage 123 which extends longitudinally in the body 8% of the valve mechanism, towar the endhaving the cover 38 which is the same end as that having the throttle actuator mechanism. There is a connecting passage 124 in the body 80 which extends from the passage 123 to the port 72 of the throttle actuator mechanism. '7 Passage 123 is drilled by drilling from the lower side-of the ,device forease of manufacture, the lower end portion of said passage'being indicated at 123a and is closed by a plug 123b, there-being no connection nication with the interior of the bore' 83.

. between the passages 123, 123a and passage 126.

connects'said passage 126 with the port 7 3 of the throttle actuator mechanism.

The valve heads 16-2 and liilthave external circumferential grooves 130 and 131, respectively, whichform labyrinthseals.

Since in the arrangement shown andpdescribed herein the valve mechanism and the throttle actuating mechends of the reduced diameter section. At the junction of head 1112 to thereby yieldingly urge the valve'liitl toward a i .60

the right, as shown in FIG; 3.

Valve head 103 has a recess 110 in the outer or free end in which is received an inner end portion of a coil spring 111, the opposite end of said spring 111 being received in the recess 91of the cover 88'so that said spring reacts between the shoulder 92 of recess 91 and a shoulder 112 at the inner end of the recess 110, so that said, spring 111' 'anism are combined in a single casting, the entire assembly is. attached to any suitable support by means of screws,

not shown, received in openings of ears 136 of the casting.

Ports Aand B are so positioned as to communicate with the valve bore or cylinder 83 as to be controlled by the inner ends of the respective valve heads. The positioning of said ports jrelative' to said valve heads is such that a slight displacement of the valve from its neutral position will close one of them and open the other, and whichever port is' open sees the crankcase pressure which exists while it is open.

' The, compression springs 103 and 111 between which the spool valve is interposed have a rate that is related to the vibrating mass of the valve in sucha fashion that the natural frequency of the system is equal to the desired governed speed. Theclearance between the bore 83 and the .valve heads 102 and 103 is quite smalLso that even withoutsealingrings for said valve heads very little air can leak through this clearance space.

Since one end of the valve bore or cylinder is connected to the crankcase, pulsating pressure in the crankcase acts on one end of the spool valve 100, the pressure pulsations causing the shuttle or spoolvalve to vibrate axially at a frequency equal to the speed of the engine. I

.When the engine speed is that desired the spool or shuttle valve 100 will be moving through its maximum amplitude, its motion being related to'the pressure pulses in such a manner that the pressures transmitted through V the ports A and B to opposite sides of the throttle actuator a piston 691 8 111 be the same and said piston will then reyieldingly urges the spool valve toward the left, as shown in FIG. 3.

Reduced diameter section 101 has a cross-bore 115 V longitudinally inwardly for connection with said crossbo're J As described above, the pressure pulsations in the crankoase are transmitted through the c0nduit 97 to theiinterior 'main stationary or substantially so.

Ifthe frequency of the crankcase pressure pulsation or exciting force is below the natural frequency of the vibratmg systerrnthe shuttle or spool valve and springs, the displacement of the mass,"will be in phase with the exciting force, but when the actual frequency exceeds the natural .fr-equenoy, the force. anddisplacement will be out ofphase. Therefore, when the engine. speed. is below the designed governedspeed, theshuttle or spool valve will move to theleft, from the centered position shown in FIG. 3, when crankcase pressure increases and vice versa. However, when the engine speed is abovethe preselected speed the valve spool will move to the right when the pressure goes up. More particularly, when the engine speed is low, port B will be opened during the high pressure portion of the cycle, and port A during the low pressure phase. This differential acting on the piston moves it in the throttle opening direction. As soon as the speed exceeds the preselected value the conditions reverse and the throtle is moved in the closing direction. I

Referring to FIG. 4, there is shown an alternative throttle actuator mechanism wherein there is a horizontal pressure chamber or cylinder 140 closed by a wall 141 at one end and having an actuator rod guide, indicated generally at 142, at the opposite end. Guide 142 has a disc or body portion 143 and an inwardly extending boss 144, said guide 142 having an axial bore 145 therethrough in which is slidably disposed an actuator rod M6 to the outer end of which there is secured a member 147 for connection with the throttle lever of a carburetor. I

Within the cylinder 140 is a piston 148 secured to the inner end of the actuator rod 146 by any suitable well known means, such as a pin 149. Ports 72 and 73 are connected to the respective ports A and B of the valve mechanism.

When the shuttle and spool valve is in the neutral position the piston 14% will remain at rest at the normal position for the throttle valve at the desired position for the preselected engine speed. When the engine speed is below the preselected governed speed the shuttle or spool valve 100 will move to the left when the crankcase pressure increases and vice versa. However, above the governed speed the valve 100 will move to the right when the pressure goes up. When engine speed is low the port B will be opened during the high-pressure portion of the cycle, and port A during the low pressure phase. The diflierential pressure thus transmitted to the throttle actuator mechanism moves the piston to the left to move the throttle in the opening direction. As soon as the speed exceeds the set value the conditions reverse and the throttle is moved in the closing direction.

The invention and its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts of the invention without department from the spirit and scope thereof or sacrificing its material advantages, the arrangements hereinbefore described being merely by way of example, and I do not wish to be restricted to the specific forms shown or uses mentioned, except as defined in the accompanying claims, wherein various portions have been separated for clarity of reading and not for emphasis.

I claim:

1. A governor mechanism for controlling the speed of a two-cycle internal combustion engine having a carburetor With a throttle valve, the pressure in the crankcase of said engine pulsating with movements of the piston, comprising:

(A) a throttle actuating mechanism having (a) a cylinder with a fluid port adjacent each end, said cylinder being closed atone end by an end wall and having a seal closing the other end, said seal having an axial opening therethrough,

(b) a piston reciprocal in said cylinder and having an axial bore therethrough,

(c) and a piston rod disposed in said piston bore and the opening in the seal and extending outwardly of the latter, the opposite end of said piston rod extending beyond the adjacent inner end of the cylinder;

(B) means adapted to operably connect the outer end of the piston rod with the throttle valve of the carburetor;

(C) valve means for controlling the throttle actuator mechanism, said valve means having a body with a longitudinally extending bore therethrough;

6 (D) a tubular sleeve in said bore, said sleeve having fluid parts therein longitudinally spaced apart;

(E) means closing one end of the bore of said sleeve;

(F) a cover closing the opposite end of the bore of the body and sleeve;

(G) a shuttle spool valve member operably disposed in the bore of said sleeve, said valve member having an intermediate reduced diameter part defining with the adjacent portion of the sleeve, an annular space, said valve member having a valve head at each end of the reduced diameter part, there being a fluid passage connecting one end of said valve member with said annular space, the ports in said sleeve being so positioned relative to the inner ends of the heads of said valve member as to be in communication with said annular space when the valve member is in its neutral position, displacement of said valve member from said neutral position causing closing of one of said ports and further opening of the other;

(H) passageway means connecting the ports of said valve bore with the fluid ports of the actuator cylinder adjacent to the respective ends thereof;

(I) a pair of compression springs in the valve bore acting in opposite directions on the shuttle valve member and normally maintaining said valve member in the neutral position;

(I and conduit means connecting said one end of the shuttle valve member with the crankcase of the engine whereby pressure pulsations in the crankcase will be transmitted to said one end of the shuttle valve member and also to said annular space and thence to said actuator cylinder.

2. The combination of a two-cycle internal combustion engine, having a carburetor with a throttle valve, the pressure in the crankcase of said engine pulsating with move ments of the piston, with a governor mechanism, comprising:

(A) a throttle actuator mechanism having (a) a cylinder with a fluid port adjacent each end, said cylinder being closed at one end by an end wall and having a seal closing the other end, said seal having an axial opening therethrough,

(b) a piston reciprocal in said cylinder and having an axial bore therethrough,

(c) and a piston rod disposed in said piston bore and the opening in the seal and extending outwardly of the latter;

(B) means operably connecting the piston rod with the throttle valve of the carburetor;

(C) valve means for controlling the throttle actuator mechanism, said valve means having a body with a longitudinally extending valve bore with longitudinally spaced ports;

(D) means closing the ends of the valve bore;

(E) a shuttle spool valve member operably disposed in said valve bore, said valve member having an intermediate reduced diameter part defining, with the adjacent portion of the sleeve, an annular space, said valve member having a valve head at each end of the reduced diameter part and a fluid passage connecting one end of said valve member with the annular space, the ports of said bore being so positioned relative to the valve heads of said valve member as to be in communication with said annular space when the valve member is in the neutral position, but slight displacement of said valve from said neutral position causing closing of one of said ports and opening of the other;

(F) passageway means connecting the ports of said bore with the fluid ports of the actuator cylinder;

(G) a pair of compression springs in the valve bore acting in opposite directions on said shuttle valve member and normally maintaining said valve member in the neutral position;

(H) and conduit means connecting said one end of the Ti shuttle valve member with the crankcase of theengine whereby pressure'pulsations in the crankcase will be transmitted 'to said one end of the shuttle valve member and to thethrottle actuator cylinder. j

3. A governor mechanism for controlling the speed of t mechanism, said valve means having a body with a longitudinally extending valve bore therein andlongitudinally spaced valve ports; (C) a shuttle spool valve member operably disp-osed in the bore of said body, said valve member having an intermediate reduced diameter partdefining, with the adjacent portion of the sleeve, an annular space, said valve member having a valve head-at each end of the reduced diameter part, said valve member having a fluid passage connecting one end thereof with the annular space, theports in saidsleeve being so positioned relative to the heads of said valve:

member as to be in corresponding relationship with] respective valve heads when the'valve member is in the neutral position, slight displacement'of said valve member from said neutral position causing at least partial closing of one of said ports and corresponding opening of the other;

(D) means connecting the'last mentione'd ports with opposite sides of the actuator piston; y 7

(E) a pair of springs acting in oppositeldirections on said shuttle valve member and normally maintaining said valve member in the neutral position;

valve member..

operably connected to opp'ositesides of said movable wall, said ports being adapted to be connected with a source of pressure;

e (C) a shuttle valve member in said valve bore having parts arranged to control said ports to oppositely effect the size thereof when said valve'member moves from a neutral position;

(D) yieldable means acting in opposite said valve member; v

(B) one end of said shuttle valve "member being adapted to be connected to va source of pulsating pressure.

6. In a governor:

a (A) a throttle actuator having a'movable wall operable in opposite directions and adapted to be connected to a throttle valve of a carburetor;

(B) means forcontrolling movements of said movable wall, said means including a member adapted to vibrate in response to pressure pulsations in the crankcase of a two-cycle internal combustion engine;

(C) yielding means, acting in opposite'directions on said member, normally retaining said member in a neutral position, the natural frequency of'said memdirections on 7' ber and yielding means being equal to a' desired 7 governed speed;

7 (D) and fluid connecting means connecting the valve means with opposite sides of said movable wall of the actuator means, said movable wallbeing subjected to substantially equal pressures on opposite sides thereof when said movable member is intthe neutral position but subjected to a diflerential of pressures on'opposite sides thereof when saidtmovable member, moves from said neutral position in either direction. V V

7. A control mechanism for controlling the operation of an actuator mechanism, said control mechanism v comprising: f

4. In a two-cycle internal combustion engine,-includ- 7 ing:

(A) a crankcase in which there are pulsations ofpressure; t (B) a carburetor with a throttle valve;

(C) a throttleactuator mechanism having a movable wall operably connected with said throttle valve;

(D) a shuttle valve vmechanism having a valve bore therein with a pair of longitudinally spaced ports communicating with the interior of said bore and operably connected to opposite sides of said movable wall; 1 t e (E) a shuttle valve member in said valve bore having parts arranged to control said ports to effect closing of one port and opening of the other port upon movement of said valve member from aneutral position; i t s V t f (F) yielding means acting in opposite directions on said valve member for normally maintaining same in neutral position; (G) means connecting onewend of, said shuttle valv member with the crankcase of ,the engine;.; 7 (H) and means connecting said ports, when open,

to crankcase pressure.v a 1 5. In a governor, for internal combustion engines having a crankcase in which there are pulsations of pressure,

said engines having a carburetor with a throttle valve:

wall;

(B) a shuttle valve mechanism having a valvebore therein with a pair of longitudinally spaced ports communicating with the interior of saidbore and (A),valve means" having a body with a, longitudinally extending valve bore therethrough; '(B)Cmeans closing one end of the bore't'of'said body; (C) a cover closing theopposite end of the valve bore,

said "cover having a fluid passage therein for connection with a' source of operating pressure;

(D) a shuttle spool valve member operably disposed in said valve bore, said valve member having an intermediate reduced diameter part defining, with the adjacent portion of the wall of said bore, an annular space, said valve member having a valve head atfeach end of the reduced diameter part and said valve member having a fluid passage {connectingfthe' end :of the 'valve member adjacent to said coveriwith the annularspace, the ports of .said valve bore being so positioned relative to the inner ends 1 of the heads ofsaid valve member as to be in communication with said annular space whenvthe valve member is in the neutral position, slight displacement oj jsaid valve member from said neutral position causing closing of one of said ports and further opening of the other, said ports being adapted to be operably connected with an actuator mechanism;

(E and a pair of' compression springs in the valve bore acting in opposite directions on the shuttle valve member and normally maintaining said valve member in the neutral position;

References Cited by the Examiner UNITED STATES PATENTS 7 --2,974,639 3/61 OConnor et al. 91+429 3,032,065 5/62 Iolley 137-102 FRED E. aNoaLrnArangprimar Examiner. 

1. A GOVERNOR MECHANISM FOR CONTROLLING THE SPEED OF A TWO-CYCLE INTERNAL COMBUSTION ENGINE HAVING A CARBURETOR WITH A THROTTLE VALVE, THE PRESSURE IN THE CRANKCASE OF SAID ENGINE PULSATING WITH MOVEMENTS OF THE PISTON, COMPRISING: (A) A THROTTLE ACTUATING MECHANISM HAVING (A) A CYLINDER WITH A FLUID PORT ADJACENT EACH END, SAID CYLINDER BEING CLOSED AT ONE END BY AN END WALL AND HAVING A SEAL CLOSING THE OTHER END, SAID SEAL HAVING AN AXIAL OPENING THERETHROUGH, (B) A PISTON RECIPROCAL IN SAID CYLINDER AND HAVING AN AXIAL BORE THERETHROUGH, (C) AND A PISTON ROD DISPOSED IN SAID PISTON BORE AND THE OPENING IN THE SEAL AND EXTENDING OUTWARDLY OF THE LATTER, THE OPPOSITE END OF SID PISTON ROD EXTENDING BEYOND THE ADJACENT INNER END OF THE CYLINDER; (B) MEANS ADAPTED TO OPERABLY CONNECT THE OUTER END OF THE PISTON ROD WITH THE THROTTLE VALVE OF THE CARBURETOR; (C) VALVE MEANS FOR CONTROLLING THE THROTTLE ACTUATOR MECHANISM, SAID VALVE MEANS HAVING A BODY WITH A LONGITUDINALLY EXTENDING BORE THERETHROUGH; (D) A TUBULAR SLEEVE IN SAID BORE, SAID SLEEVE HAVING FLUID PARTS THEREIN LONGITUDINALLY SPACED APART; (E) MEANS CLOSING ONE END OF THE BORE OF SAID SLEEVE; (F) A COVER CLOSING THE OPPOSITE END OF THE BORE OF THE BODY AND SLEEVE; (G) A SHUTTLE SPOOL VALVE MEMBER OPERABLY DISPOSED IN THE BORE OF SAID SLEEVE, SAID VALVE MEMBER HAVING AN INTERMEDIATE REDUCED DIAMETER PART DEFINING, WITH THE ADJACENT PORTION OF THE SLEEVE, AN ANNULAR SPACE, SAID VALVE MEMBER HAVING A VALVE HEAD AT EACH END OF THE REDUCED DIAMETER PART, THERE BEING A FLUID PASSAGE CONNECTING ONE END OF SAID VALVE MEMBER WITH SAID ANNULAR SPACE, THE PORTS IN SAID SLEEVE BEING SO POSITIONED RELATIVE TO THE INNER ENDS OF THE HEADS OF SAID VALVE MEMBER AS TO BE IN COMMUNICATION WITH SAID ANNULAR SPACE WHEN THE VALVE MEMBER IS IN ITS NEUTRAL POSITION, DISPLACEMENT OF SAID VALVE MEMBER FROM SAID NEUTRAL POSITION CAUSING CLOSING OF ONE OF SAID PORTS AND FURTHER OPENING OF THE OTHER; (H) PASSAGEWAY MEANS CONNECTING THE PORTS OF SAID VALVE BORE WITH THE FLUID PORTS OF THE ACTUATOR CYLINDER ADJACENT TO THE RESPECTIVE ENDS THEREOF; (I) A PAIR OF COMPRESSION SPRINGS IN THE VALVE BORE ACTING IN OPPOSITELY DIRECTIONS ON THE SHUTTLE VALVE MEMBER AND NORMALLY MAINTAINING SAID VALVE MEMBER IN THE NEUTRAL POSITION; (J) AND CONDUIT MEANS CONNECTING SAID ONE END OF THE SHUTTLE VALVE MEMBER WITH THE CRANKCASE OF THE ENGINE WHEREBY PRESSURE PULSATIONS IN THE CRANKCASE WILL BE TRANSMITTED TO SAID ONE END OF THE SHUTTLE VALVE MEMBER AND ALSO TO SAID ANNULAR SPACE AND THENCE TO SAID ACTUATOR CYLINDER. 